When listening to music, four notes that each lasts one beat could be represented on a staff by one whole note

two half notes and two quarter notes

two whole notes and two half notes

four quarter notes

the answer to your question is c.

if you read the house of usher you should know that the house was haunted

chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances. these processes are called chemical reactions and, in general, are not reversible except by further chemical reactions. some reactions produce heat and are called exothermic reactions and others may require heat to enable the reaction to occur, which are called endothermic reactions. understanding chemical changes is a major part of the science of chemistry.